Relationships to unsaved objects throw validation error

[dallonf]

Say I have a Topic object which has_many :posts, and when I create a Topic, I want to also include an opening Post.

If I assigned a Topic to the Post (or vice versa) without first saving the Topic, post.valid? will return false and post.errors will include "Topic must not be blank". I believe that since the topic relationship is set, post.valid? should return true. (although if the Topic is not saved first, post.save should fail)

A workaround is to use topic.save and handle a false result from that, but I personally prefer to use the valid? methods before saving.

[xaviershay]

Turn off auto_validation on the relationship.

Related, I typically use this monkey-patch (which I don't think will fix your problem exactly but will fix similar problems):

module DataMapper
  module Validations
    module AutoValidations

      # Always skip auto-validations on primary keys, it turns nested saves into a whole world of pain.
      def skip_auto_validation_for?(property)
        (property.key? && !property.options[:auto_validation]) ||
        (property.options.key?(:auto_validation) && !property.options[:auto_validation])
      end

    end
  end
end